Charge



June 1e, 195s E. @RIN 2,642,423

' UREA-OLEFIN COMPLEXES )vg Z JEP/7154770 IN VEN TOR.

n, 'Everett Gori/1.

Pwfgw Patented June 16,v 1953 d j v(Everett Gorin, Castle Shannon,'Pa"assignorfto Socony-Vacuum Oil Company,IncorporatecLa k corporation of New York v Application September 13, 1949,',Serial s claims; (C1. 26o-96.5)

This invention has to do with the separation of hydrocarbons and hydrocarbon derivatives of diiierent molecular conguration from mixtures containing the same, and also has to do with the preparation of new and-novel compositions.l

.1. FIELD OF INVENTION Numerous processes `have been developed.V for the separation of hydrocarbons and hydrocarbon y .10

derivatives of different molecular conguration by taking advantage of their selective solubility in selected reagents or solvents kfrom which they may later 'beseparated Exemplary of hydro# carbon separation procedures is the Edeleanu process, wherein paraflinic materials are sep' arated from aromatics `by virtue of the greater solubility of aromatics in liquid sulfur dioxide. Lubricant oil solvent refining processes, solvent deasphalting, solvent dewaxing andthe like are lfurther examples of the separation of hydrocarbons of different molecular configuration. Typical'of selective solvent proceduresvfor separating hydrocarbon derivatives is theseparation of paraffin wax', monochlorwax and polychlor- Waxes, with acetone as the selective solvent.

This invention is concerned with the general eld outlined above, but based upon a different and little-known phenomenon, namely, the differing ability of hydrocarbons and hydrocarbon derivatives to enter into and to be removed from certain crystalline complexes. Y herein, the term complex broadly denotes a combination of two or more compounds.

This invention is predicated upon the knowledge that urea forms complex crystalline compounds to a varying degree with various forms of hydrocarbons and hydrocarbon derivatives.

II.` PRIOR ART For some years it has been known that various isomers of aromatic hydrocarbon derivatives Yform complexes with urea. Kremann (Monatshefte f. Chemie 28, 1125 (1907)) observed that complexes, designated as double com'- pounds, of urea and the isomeric cresols are stable at different temperatures. Schotte and Priewe (1,339,859) later separated meta-cresol from the corresponding para isomer by selectively forming a meta-cresol-urea complex, which was described as an addition compound; thel latter compound was separated from the para isomer and then split up by distillation or with water or acidto obtain pure meta-cresol. The

As used nfectant(Priewe-l,933,757). Bentley and Catlow (1,980,901) found a numberfof aromatic amines `containing, at least' one basic amino `group "capable of :forming double compounds" with certain isomeric phenols. It has also been shown that trans-oestradiol can bej separated from the corresponding cis-compound byr forming a diicultly soluble compound of urea and transf-oestradiol (Priewe-2,300,134).

- The forces between urea and the compounds of the foregoing complexes are due to specic chemical interaction between theA various functionaly groups.

One heterocyclic compound, 2-:6 lutidine, has been found-to l`form a crystalline compound :with

' urea, thus affording a 'meansof separatingthe lutdine from beta-f and -gamma-picolines (Riethof-2,295f,606) v Comparatively few aliphatic hydrocarbon "ole-v rivatves have. been vknown to date to form complex compounds with'urea""`In German patent application B v190,19'1',"IV. d/12 '-(Technical Oil YMission,` Reel 143'; Library of, Congress, May 22,

194:6).` Bengen described a method for: the separa tion` of aliphatic oxygen-containingcompounds Y(acids, alcohols, aldehydes, esters and,A ketones) andxofafstraighty chain hydrocarbons-'of at least -six carbon 'atoms from mixture-containing the sama-the method being predicatedupon the abilityy ofsuch` compounds vand hydrocarbons to formnAdditionsProdukt, with urea. In the Technical Oil Mission translationof `the Bengen application,v however, the `urea complexes were designated fadductsf which term apparently stems from the anglicized addition product.

III. DEFm'lTIONs I "From ithe foregoing discussion j' of' prior' art Y 11), it will be clear that a variety ofterms have been applied to urea complexes. Thejlatter have beenv lrather loosely described as rdoubl'e compounds, Haddition compounds, diiii'culty soluble compounds," Additions-Produkt, andY adducts All of these terms are somewhat ambiguous in thatthey'have also been used to describe products or complexes of different charaddition compound of metal-cresol and urea was shown thereafter to have utility as a dis- L acter than "theiurea complexes under consider'- ation, .Thisf is "particularly sok with' the term adducafand 'therelated 'term unadducted materials. `While the, term adduct is simple and convenient;` itfs' aiiurifortunate designation, inasmuch as it 'confusesjthese complexes with otherk substances known'fin the fchemical.v art. Speiciiiially',""fadduct has been applied to Diels- Alder reaction products, 'formed by reaction vof f'eachY other'.

Further ambiguity is introduced by the termv adduction, which has been defined as oxidation (Hackh). L: l

To avoid the foregoing conicting terminology,

several related terms have beenlicoined lto define with greater specificity the substances involved4 in the phenomenon undern consideration. As contemplated herein and asused throughout the speciiication and appended claims, thepfollowing terms identify the phenomenon:

`Plexad-al revertable associated complex comprising a piexor, such as urea, and at least'one `othercompound; said plexad characterized ,by 'reverting ordecomposing, underthe influence ,-,of heat and]or, variousesolvents, to its original constituents, namely,=a plexor and at least ...o 11ep1eXa.r1d.z an; Blexand--a compound capable of forming a plexad with 'a plexonsuch as urea; compounds of thisharacter diierwintheir capacity to ,t if orm plexadsL depending .upon Avarious factors ttdescribedtherenafter;,i Y Antipiex-a compound incapable Aof* forming a Plexor-a compound capable of forming a l, .fwith aplexand; such as urea, ,Blexate-toform afplexad.

plexad PleXation-The act, processor eiect of plexatlng ' 1v.Y STATEMENT oF INVENTION llthasrnowfbeen discovered that, by.. selective l,pleiation witnureaf, certainaliphatie hydrocarbons and,` aliphatic .hydrocarbon derivatives of zvarying; degrees 'of saturation (or unsaturation) can ,be .L separated, in.. the form of (their corresponding plexads,i from a mixture containing the l same.; Qne :particular selective plexation in- A,volvesrseparationsof kmore saturated straight .chain hydrocarbonssandhydrocarbon derivatives .from lesssaturat'ed straight `chain hydrocarbon .and hydrocarbon vderivatives, forv example, a saturatedf Yparai'iin froma -Amono-olen', particplarly when the olefin -group is relatively centrally positioned in the molecule; also a monoolelin from a poly-olen, particularly when the olefin groups `are relatively centrally positioned v,andare spaced-,an` appreciable distance from Another selective KVplexation involves ns'eparaticm of ajstraight chain hydrocarbon, or ,hydrocarbon,derivative, having a double bond at vor* close toatermalearbon atom, from a hydrocarbon, `or,hydrocarbon` derivative, having a double bond4 moregcentrally positionedin the' hydrocarbon chain. The separation procedures are -effective wherilthe` aliphatic hydrocarbons and'aliphatic hydrocarbon derivatives present inthe mixturesv subject to` plexation have the same orga different number of carbon atoms. Selective plexation is also eieetive when the Yaliphatic hydrocarbon derivatives have the same or different substituent groups.

""As contemplated herein, the invention makes possible the. separationtof onel or moreplexands from a. mixture 'centainins 4the .sainersuch ,plexand or plexands being separated in the form of a plexad` or plexads which, as described in detail hereinbelow, revert to the plexor, urea, and the plexand or plexands under certain conditions. The separation, therefore, is an excellent means for obtaining, in pure or concentrated form, one or more plexands or antiplexes whichever is the desired material; The invention also provides a means of forming new compositions of matter, namely, a number of plexads which may be used as a source of a plexor, urea, or as a source of a plexand.

v. OBJECTS It is an object'of this invention, therefore, to provide'an eiective means for separating hydrocarbons and hydrocarbon derivatives of diferent degrees of saturation, or unsaturation, from mixtures containing the same.

It is also an object of this invention to selec- .tively .separatenJ Straight e han saturated.. hy-

drocarbon `from a mixture containing ,the saine and a straight chainr unsaturated hydrocarbon.

`,A more particular object is the separation of a straightA chain fparafiin iromA a straightlchain mono-oleiin, especially when the olen group i's relatively centrally positioned in the molecule.

,A related Objectis thevseparation of a straight chain `saturated paraiiii derivative frordahixture containing tl'iesarnev and'fa straightc'hai'n unsaturatedparaffin-'derivativa A particular object. is these'parationfo'f l'a straight chain saturated acid Vfrom alstraight Vchain,''unsaturateld acid. l Y A further object is vthe provision of a selective separation oir a straight lchain mono-olen'from `a mixture containingthe same and a straight chain poly-olefin.Y particular object 'is the Vseparation of a straight'chain'mono-olefin from ,a straight chaindiolefin, v@Specially `when the loleiin groups arefrelatively centrally positioned and are, spaced vvan,appreciable distance from `each other. yA related object-is the separation of a straightchairrmono-oleiinic paraliin derivative fromamixture `containin,gthe same and a straight chain poly-olenic'paraiiin derivative. .Amore particularobject is thel separation of a straight chain mono-olefinic acid ironia straight ,chain polyoleiinic acid.'

An additional obietfi'stlie separation of'a straight chainl mono-olefin`-having'-the double bond -at a terminal carbon atom, from a mixture containing the sameY and a straight chain monooleiin having the'doublebondmore centrally positioned in the hydrocarbon fcliain..v A corresponding object is the separation of a' straight chain mono-olefin vhaving andnternal double bond from a 'mikturemcontaining' the samean`d a straight chain mono-olen having an internal double bond more centrally positioned in the chain. i o

Another object is the provision of a continuous method of separation rof said plexands and antil plexesrvvhichymlethod is flexible, capable of relatively sharp separation,"an'd not highly demanding of attentionandnoiutilities`such as heat, re-

frigeration, pumpingfpoiver; andthe like.

Still another object 'isv to provide a plexand or plexands substantially free of an antiplex4 or antiplexes. A corresponding object is the provision of an antiplex'or antiplexes substantially free of said plexand or plexands.J f Another object is to "provide a neu/and novel kclass or sub-'olassjjof e plexads comprising` 4 a nlexardtsndiiiea fr; rift.

, s Other objects and advantages of the invention -will Ab e apparent from the following description.

Y v1. INVENTION 1N DETAIL As' indicated above, it has been found that the foregoing objects are achieved by selective plexation with urea (a pleXor) of a plexand or plexands. Y

' (l) Merenda-A plexand, as dened above, is a compound cap-able of forming a plexad with a plexor, such as urea. Contemplated herein as plexands are avariety of parafnic compounds.

(a) Parains. Bengen, .identied above, has disclosed that straight chain paralins having at least six carbon atoms per molecule form complexes, or as defined herein plexads,I with urea. Such parafiins, therefore, are considered as plexands in the process of this invention. V

Typical'of such paraiiins are the following:

n-I-Ieptane n-.Nonane n-Octane n-Decane, etc.

(b) Unsaturated compounds. It has now been found that normal, alpha oleiins having no more thantwo additional non-terminal double bonds and at least about seven carbon atoms per molecule, are plexands. It has also been found that stronger plexads are formed of such normal, alpha oleflns, than of the corresponding olens having a double bond more centrally positioned in the carbon chain. In other words, the forces between urea andthe olefin making for plexad Representative normal, alpha olen plexands are the following:

1-heptene 1pentadecene l-octene 1hexadecene l-nonene l-heptadecene l-decene 1octadecene 1,1'7-octadecadiene Y 1nonadecene i,3 decadiene lA-decadiene 1,9-decadiene 1eicosene l-undecene 1,19-eicosadiene 1,l0undecadiene 1-docosene 1dodecene 1tricosene 1,11-dodecadiene 1-tetracosene l-tridecene 1-hexacosene (cerotene) l-tetradecene l-heptacosene lA-tetradecadiene l-octacosene (c) TerminaZZy-substituted parans. As described in several related applications, Serial Nos. 115,551, 115,518, 115,514, 115,515, 115,516, now abandoned, 116,593 andl15,517, nled concurrently herewith, certain terminally-substituted straight chain pareti-Tins are pleXands. These parafiinic compounds have been represented vby general FormulaA:

(A) X(CH2)nCHs wherein n is a whole number and wherein X is a substituent group of the character described below, with n and X being interrelated. y

The substituent group X canbean inorganic u "wherein'Z a'h'alogen atom,etc.; (d) 'oxygencontaining substituent:`

droc'arbon group, CO, O ,l CI-IzOH, l CHz'COOH, elle.; l (e) 'cyclic substituent: f

'cyclobutyL i cycloalkyl ksuch as cyclopropyl,

cyclopntyl, cyclohexyl, cyclohepltyl, chlorl cyclohexyl, etc.; aryl such as phenyl and ".chlorphenyl; hetero such as'thien'yl C4338, furyl 04H30, pyrryl C4H4N, pyridyl C5H4N, thiazyl CaHzNS, pyrazolyl CaHaNz, piperyv 'dyl CsHiuN, etc.; -V (j) alkyl substituent: methyl; (g) alkenyl substituent: vinyl; (h) haloalkyl substituent z' cli'chlorrnethyl Cl2CI'I etc.

The substituent group (X) can be any of the types outlined above subject, however, to one important consideratiomnamely, that of geometrical size as related to the number of carbon Y atoms in the chain. The .width of the substi-v tuent groupl is the geometrical feature to be considered, vand this is the cross-section of the group taken in a direction perpendicular to the bond joining theV group'lto the carbon chain. This distance is taken atthe widest portion of the group and may be convenientlyv given a quanti` tative measure as the distance from between outer covalent radii of the two most widely separated atoms along the cross-section of the group where the covalent radii are those given by Paul- -ing (Pauling Nature of The Chemical Bond;

Cornell University Press; Ithaca; N. Y.; 1939). The width determines the length of the carbon chain required to obtain plexation at about 25 C. with a saturated urea solution, a plexor.v In the case of `composite groups of the type COY, CHzC'OY and CH2Y, wherein Y is a non-aliphatic radical `such vas c hlorineor amino, the C'= O, CHzCO `and, CHzconstituents, respectively',-fare considered as part of the carbon chain and the width computed is that for the radical YL] y v, l

Thef widths of a number of typical groups computed,` according to the method given above are `listed in order of size in Table I below:

Table I jWidthr ofv various groups in 11' CN 1.20 F 1.28 O H 1.93 COOH l 1.93 C1 1.98 NH2 2.11 -CQNH2 2.11 Bf v 2.28 CI-I3 2.36 I 2.66 SI-I 2.67 NO2 P- .L SOsI-I 3.69 Thienyl- The correlation between .the widt fnot the terminal substituent and thellengthA of A the carbon .chain required for plexad formation at 25 C. is an approximate one, This relationship depends to some extent upon the nature of the substituent as Well as upon'the Width of tliesubstituent. ,For example, in the'casjeA 'Where two substituents are of the vsame siz'e, the group which imparts a higher meltingpointqto the substituted paraiin will frm'the stro"" `fer plexad, i. e. will form a plexad when the chain is somewhat shorter in length. Caproio aid, melting point-.1.5D C., thus preferentially fo Ins a plexad with saturated urea at 25 C jwhen a 'mixed with n`hexyl alcohol, melting point -51 .6 C.

Only the carbon atoms in the chain. are con- L sidered to contribute to; fe chan'lerigth, that is, atoms such asV oxygen, s'ulfu, nitrogen, etc., are not included in' the atom total.A Accordingly, then, the straight chain compounds contemplated herein include straight chain aliphatic hydrocarbons and straight'chain aliphatic hydrocarbons in which one ormore of the carbon atoms of the chaini'have been replaced by such atoms ask oxygem sulfur, Anitrogen, :and vfthe like.

It is possible, rhoweven'to give the. unequivocal limits forthe relationr between Width. of the terminal substituentandlsizeof'the carbon chain required for plexation with urea at 25. C.` These y limits are set forth'v in Table'II below:

Table.. 11e-cne; n, ,between ffwidt dfi/:iterminalsubstituntgdndminimum chain length orrea plejcat'on at 5 Y v:cyanate and isccyanatefn-hexyl cyanate, n-hexyl isocyanate, n-decyl cyanate n-decyl isocyanate, n-hexadecyl cyanate, nexadecyl isocyanate, etc. thiocyanate and isothiocyanaten-decyl thiocyanate; n-decyl isothiocyanate;

n-octadecyl thiocyanate; n-octadecyl isothiocyanate; etc. sulfur-,containing compounds AmercaptoV n-octyl mercaptan, n-dodecyl mercaptan, n-hexadecyl mercaptan, n-octadecyl mercaptan etc. sulfide (SR)- methyl, n-octyl sulde; n-butyl, n-dodecyl sulfide;

amyl, n-hexadecyl sulfide; etc. sulfaton-dodecyl sulfate; n-hexadecy1 sulfate; etc. "sulfonyl halide- .n-decyl sulfonyl chloride, n-dodecyl sulfonyl bromlde, n-hexadecyl sulfonyl iodide, etc. oxygen-containing compounds: hydroxyn-heptanol-l; n-octonol1; n-decanold; n-dodecanol-l; n-hexa'decanol-l; octadecyl alcohol;

e carboxyl v n-valeri'c. acid; caproic acid; n-heptylic caprylic acid; pelargonic acid;- lauric myristi acid; palmitic acid; stearic arachidic acid; behenic acid; lignoceri'c cerotic acid peto.

acid acid acidj acid etof b t i i nu yl ketone; methyl, n-he t l ketone;

ethyl, n-hexyl ketone; p y ether-- d1{n-butyl) ether; ethyl, n-pentyl ether; difut pentyl) ether; etc. Ves er di u-amyl) succinate' n-but l stearat (e) cyclic ubsntuent: y e' etc 1-cyclopropyln-octadecane l-cycloheXyl-n-hexadecane l-phenyl-n-octadecane l-thienyl-n-octadecane; etc.

substituent it-gegane;

imethyl-ii-octadecane ctc. (g) liuloalky] substituent:

i,l-dichlorlnethyl-n-decane, etc,

It is to be understood that terminally-substituted straight chain compounds containing a second terminal substituent on the opposite terminal carbon atom, are also contemplated herein as plexands. Such disubstituted compounds are also subi ect to approximately the foregoing relatlonshlps of terminal group Width and chain length. Compounds of this character are represented by the following general Formula A':

wherein n is a whole'number, and X and X are the same or different and as delined above.

Illustrative of such compounds are the following:

m any1 1,10-dichlor-n-decane; 1,8--n-.octaneV diamine; 1,10-n-decane diamide; l,l2-n''dodecane dithiol; l,iS-disulfo-n-octadecane; etc.

(d) TerminaEly-substituted defina-Straight chain oleiinic compounds having a termina-l substituent and not more than two non-terminal double bonds, are also considered :as plexands herein. The terminal substituentsA are of the character described above in connection with the related para-inns VH1) (c). Here too, the same `relationship of Widt of terminal substituent and carbon chain lengthis an important ccnsideration. The relationship shown above is in operation with the olenic compounds subject, however, to some influence of the degree of unsaturation. .In some cases, the presence of one double bond will require a chain of one or two more carbon atoms than are shown in connection with VI(1) (c).

By Way of illustration, the following terminally-substituted, normal olens are typical plex- .andst n-Octadeceneamide;

Oleic acid; Y Oleyl alcohol; n-Octadecenyl mercaptanr.

Included also as plexandsare terminally-substituted, straight chain non-alpha olefins having lessthan three double bonds per molecule. Here L too, the width of the substituent group and the number of carbon atoms in the chain areV interrelated, and the values .given above for com? pounds represented by general Formula A are substantially in operation.

By way of illustration, the following compounds typify terminally-substituted, straight y chain non-alpha oleiins:y

It shoiud be noted thatl z-ethylhexyi, n-o'ctyi' fumaratey forms a plexad with urea,v thus demonstrating that a relatively small degree of branching can be tolerated, that is, one ethyl group in a linear chan'containing eighteen carbon atoms.

However, di(2-ethylhexyl) flumarate does not form aplexad under thesame conditions, ap-

parently having too high a degree of branching.`

Another feature to be notedv is the failure of din-amyl) fumarate to form a plexad with urea at C; This demonstrates the insufliciency of the amyl chains, for at least one of the chains should contain at least six carbon atoms.v For example, di(n-hexyl) fumarate forms a plexad under the same conditions. Dioleyl maleate, however, does not form a pleXad under these conditions, evidence that the degree of unsaturation, three double bonds, is too high for plexad formation.

It is to be understood that terminally-substituted straight chain olens containing a second terminal substituent attached' to the opposite terminal carbon of the chain, are also contemplated as plexands. These disubstituted olefins are subject, too, to the terminal group width and chain lengths applicable to the substituted olens above.

.Typical of disubstituted olens having atleast one terminal substituentare the. following: Chloro oleic acid; v y Ricinoleic acid; etc;

(2)?. Secondary planmatig- The compounds de-A scribedbelow are secondary plexands in the processes of this invention.

` plexands are primarily straight chain in character with but little branching. In general, these paraiins should contain atleast about ten carbon atoms in a straight chain, with the branch chain being attached to another carbon atom of Vthev chain and with the branch chain having less than three carbon atoms.

l0' Illustrative of such parains is 2methyl-n-hexadecane (b) Glenna-Straight chain, non-alpha olefns having less than three double bonds and having at least about seven carbon atoms permolecule, form plexadsV with urea. plexads of such olefins 'are not as strong as those As indicated above,

formed with the alpha olens defined above.Y

The difference in the forces attending a plexad` of al-olen and a plexad of a 2-olefin is, therep fore, substantially lessl than the corresponding difference with a l-olenand a 4, 5- or 6-olen. Applying this relationship, a more effective separation is made of a 1olen from a 4-olen, than of a l-olen from a 2-olen. In the latter instance, however, a considerable upgrading of the 1olen content isrealized, particularly by repeated contact with urea.

Representative non-alpha olefins behaving as secondary plexands are the following: r

2-octene 2,8-decadiene 3-octene 2undecene ,l-octene 5-undecene 2nonene V6 -dodecene Y 3-n`onene 2,6-dodecadiene 4-nonene f 6,- tridecene 2-decene 7-tetradecene 3-decene B-heptadecene 4-decene n 9-octadecene 5decene Both thecis .and Vtrans form of the olens areA contemplated. herein; however, the vtrans com- 'pounds .will general-ly. form the stronger plexad.

(c) Non-terminally substituted compounds-' Secondary plexandsy alsoinclude non-terminally substituted, straight-chain ;compounds charac#-A f terized by general Formula B:

(B) Horonb'fcmonbt'onl wherein r and m are integers, the sum of which is equal to or different than n`-2, and'r`1 t and X are as denedabove. i

substituent group (X) roughly determines the minimum carbon chain-:length required for plexation of a secondary'plexand. "The length is the projection along the bond joiningthe group 4to the parent hydrocarbon of= the distance `from the center ofthe carbon atom to which the group is attached, to the 'cente'rof the atom` whose covalent radius shell extends furthest in thedi# i ,A rection ofrsaid bond, plus the covalent radius of said bond. The minimum chain length isalsoto some extent a function of the positionsubstituted as well as of the chemical nature. of the group. Thus, in compounds of this type, the

minimum chain length required for ple'xaticnr.Y

length` of.; group HaC'(CII2)r-f, if r is small enough so that. this..

is determined by the alkyl group is shorter in length than the'su'b-,L stituent group (X). It is possible, bearing this relationship in mind however, also 'to'g've rather.

wide limits in the correlation of Vgroup-l'engthf with the minimum chain* lengthA required for plexation. The lengths o f various groups are given in Table III,'`below, while `the correlation of chain lengths with .group lengths`is given-'r in Table IV, also provided'below: I

NH2 V- 2.17

assenza -CHzCl 3.11 -'-C2H5` 3.19 -CN 3.25 -SOaHr 3.37 -I 3.43 yclohexyl average) 5,09 -Phenyl 5.69

Table I lli-#Correlation between'fleng'thl; of hone' terminally substitutedY groups andV minimum chain length requiredfor urea plexation at'- Minimum Chain "Length Igength in A Numberof `Gai-bou "atoms Again, it is'to be understood that these limits apply for plexation at about C. Heretoo, the minimum yriumber of carbon atoms -in the chain is somewhat lower'f'or plexation at lowentemperatures, Vbut generally not.more than one or two, carbon atoms' lower. In the samev vein', a correspondingly higher 'numberr of carbon atoms Willfberequired inthe 'carbonchain for a rise in temperature. Y

Secondary plexands .represented by general Formula B, above, are typified by the following:

Zfchloro-n-tetracosane;

(3) VAntiplaiL-iln'antiplex, as defined above, is a" compound incapable'bf; forming a plexad withaplexonsuchas urea.

ACompounds which have been found tobehave as antiplexes inv the sense-that they areincapable (4) Platon-The plexor usedV herein is'urea,` whichV is in solution in a singleor multiplecomponent solvent. yThis'solution should range from partially saturatedto supersaturated at the temperature at which it is contacted with a plexand or `with a mixture containing one or more plexands and antiplexesrand. in. many cases. it

with urea` 'at'about '25 C.,

feo

will be found convenient to suspend a further.. supply of urea crystals in thesolution, haridli'ng` a degree sufficient to permit separation by'giav-A ity, centrifuging, etc.

The solvent should be substantially inert to the plexand and to the compounds of the mixture and also to the urea. Preferably, it should also beheat lstable,44 both alone and in contact with urea, at temperatures atwhich the desired plexad is not heat stable.

As indicated above, the solvent may be either singleor multiple-component. It is sometimes convenient, particularly where .the plexad is sep arated by gravity, to utilize'a two-component system, as water and an alcohol, glycol, amine or diamine, and preferably a lower aliphaticl .alcohol such as methanoljor ethanol, .ora watersoluble aliphatic amine such as piperidine.-

lSuch a solvent, partially saturated tosupersaturated with urea, lends itself readily to aA continuous process for separation by plexation.

Solutions containing sufcient Water to minimize the solubility of thehydrocarbon deriva tives in the urea solvent, areqoften-employed. The

minimum quantity of water requiredin such instances depends upon the` polarity andv the.

molecular Weight of the hydrocarbon derivative, oriplexand, being'treated and, in-general, this quantity will'begreater with more polar plexands," and'with" lower molecular weight compounds.

IIn! certain cases the use of single-component solvents is advantageous; Single-component solventsoth'er than `alcohols may be employed, although' they are normally not as useful-as the lower aliphatic'alcohols. Glycols may be 'employed as single' solvents-yet ethylene glycol is generallynot suitable in gravity separation foperationsdue'to the'ihigh density of the urea'.saturatedlsolvent.'` Thehigher glycols and particularly the butyleneglycols may be advantageously. employed. Diamines such as diaminoethane, -propane and -butane may likewise be employed.' Additional' useful solvents include forrnic acid, .acetic` acid, formamide, acetonitrile, branched chain hydrocarbons, Vcli-alkyl others", @esters .'of: `carboxylic acids, 'and alkyl halides; althoughformic.iacid, Aacetic acid and 2 formamide are subjecttotheV same limitation as ethylene glycol; f

lSolvents generally useful when mixed with suicient water, .ethylene glycol or .ethylene diaminegto'frender them. substantially insoluble in the derivatives being treated, are selected from the classici alcohols. such methanol, ethanol,..pr'opanol, etc.; ethers such as ethylene glycol dimethyl ether; and amines such as trimethylamine, hexylamine, piperidine. When gravity separation is employed, the mixed solvent is preferably subject tothe restriction that the density after saturation with urea must be less than 1.0-1.1.

(5) Typical separatiohs-ln order that this invention may be more readily understood, typical separations are described below with reference beingL made tothedrawings attached hereto.

(a) Separation of VmoreV highly unsaturated compound from less` highly Vunsaturated compoimdf-The procedure which may be employed in effecting the separation eta more `highly `un saturated compound from one less unsaturated, Y

may be essentially the sameas that described in copending application Serial No. 4,997, led January v28, 1948. The plexand obtained'in decomposing the plexad obtained in a urea-treat,-

ment of a mixture oisuch compounds is very'A pure provided that only. the less unsaturated compound forms .a- `plexad and provided the plexad be carefully freed 4of occluded antiplex before it is decomposed, For example, substantially pure oleic acid is separated from the plexad obtained in the treatment of a mixture of A the.`

same and linolenic acid, ,for the latter doesnot form a plexad. 4 f

In Figure 1, a Vcharge comprising aplexand and an antiplex, for example oleic acidand linol lenic acid, respectively, enters through line I,

to be contacted with urea solution from line 2,y

and the charge and .folution are intimately mixed in 'mixer 3. In case the charge undergoing treatment is rather viscous at the temperature oiplexad (oleic acid-urea) formation,

intimate mixture of urea solution and charge,

the mixture flows through line 6, heat exchanger l, and'cooler 8 into settler e. There may be some or a good portion of plexad (oleic acid-` urea) formed in mixer 3, but in generaL'itis preferred to operate mixer 3 at a. temperature somewhat above that conducive to heavyr forma tion of plexad. Then'in heat exchanger l, the temperature of the mixture is reduced, and in cooler 8 adjusted, so 'that the desired plexad is formed. It will be recognized thatthisshowing is diagrammatic, and that the heat vexchangers and coolers, heaters, etc.,'shown will be of any type suitable, as determined by the physical characteristics ofthe materials being handled.

For the mixture in question, temperatures of operation in the range of 2.550 C. are most suitable. When relatively low molecularr weight compounds, for example those containing from 6-10 carbon atoms per molecule, saturated urea solutions in polar solvents are employed attemperatures from *10 C, to 20 C.. When the compounds contain from 10e16 carbon atoms per molecule, saturated urea solutions are also employed, but at temperatures in the range .of 15 C.-30 C;

It should be noted, however, that many compounds such as the esters of stearicl of urea required.l

wherein the `diluent is removed, pass overheadI by vvapor line I2 and eventually to use throughline 4. Recoveredfantiplex (linolenic acid) passes fromthe system through line'IS.

will be dispensed with.

Plexadiand urea solution; withdrawn vfrom settler 4lrlthrough line I4 are passed through. heat exchanger v'I and heater I5 to enter settler;v lthrough line V5.1 In this operation/,'theftemf f perature is so' adjusted that the plexand (oleic acid) isvfreedfrom thev plexadv and, in settler I5, the plexand rises to the top to be recovered fromthe system by means of line I8. The-urea solution, thus reconstituted to its original con.i

dition by return toit of that portion of the ureay i which fpassed into plexad, is withdrawn from. settler II by line 2v and returned to process'.

Naturally, ina process of this kind there lare minor mechanical and entrainment losses of urea solution, etc., and urea solution' make up` is provided for by line I9.

"In many cases, the separation kofu-'plexad and solution from `antiplex may be conducted with greater facility ina centrifuge operation, Such a' setup is shown in Figure 2, wherein only the' equivalent of. that portion of Figure 1 centering about settler 9 is reproduced. Again in diagram form, the cooled mixture containingantiplex,

'plex-ad-v and ureaA solutionenters. centrifuge 20 throughline 6. In many cases, it will be desirable to utilize a carrier liquid in known manner in this operation and that liquid may,l be introduced by line ZI.y Antiplex will be carried oi Y through line IIJ, and pleXad, urea solutionyand (b)y Sepamtzon of saturated param@ from'` rolefinmln the caser where a straight rchain sat- From cooler V8, the pleXad-containing mixture flows into settler. 9. lThis settler -is preferably so managed that there is an upper phase of antiplex (linolenic acid),V an intermediate phase of urea solution, and a lower region containing a slurry of plexad in the urea solution. The incoming mixture is preferably introduced. into the solution phase, so that the antiplex maymove upward and plexad downward, through some little distance in the solution, to per-mit adequate separation of plexad from antiplex' and antiplex from plexad. 1

Antiplex will be removed from settler 9 by line I and introduced into fractionator II,-

f ur'ated paraiiin and a straight chain olefin present in a mixture each'form `a plexad, a' concentration of the saturated parafn will be obtained.

The-sharpness of separation will be greater, the greater the difference in the strength of the` plexads formed with` the two types of pure compounds. shorter the carbon'chain length of the compounds andthe more centrally positioned the double bond of the o-len .For example, a more concentrated n-octane can be obtained from a lmixtureoi the same and n-octene-2; whereas,

an upgrading'of n-octane content isl obtained with amixture of the same and n-octene-1. Also, it.- is more diiicult to@ 'obtain separation between nedodecane and n-dodecene-Z, than betweenn-octane and n-octene-2.

The following serves to illustrate a procedure for obtaining 'separation between a plexand,

nfoctane, and a secondary plexand, `n-octene-Z.

l'I-hisprocedure .is similar to= a sweating for a sol.

Vent .fsweating procedure used inthe refining of slack y waxes, as is shown, diagrammatically I in Figure-,3. f

In Figure; 3,. a slurry of solid urea in a saturated-,urea solvent, which is preferably an aque# ous alcoholicsolution, is pumped fromvline .3IL into; a. turbo mixer-32 where A it is lagitatedl with.

Olb-y viously if no diluent be used, fractio'nator II' In general, this will be greater, thel Y after referred t'o for simplicity as plexand'and antiplex, respectively), which enters through line 33. An immiscible solvent charged through line 34 is also preferably employed; such as a light cut from a straight run naphtha in case the plexand and antiplex have: 1) a relatively high viscosity; (2) an appreciable solubility in the urea solvent; or (3) greater density than the urea solvent. The amountfo-f` excess solid urea employedA should be suicient so that after the' plexation is completed the urea solvent remains substantially saturated with urea. Y

Internal cooling means may be employed in 32 to further cool the mixture and remove the f heat evolved during the plexation. The temperature employed. in 32 `vvill depend'upon'the chain length of the plexand and antiplex. If

the chain length is such that itis not more thanone or two carbon atoms greater than the minimum-required .toobtain' plexation with the pure plexand at 25 C., then temperatures inv the rarge5oil-1O9'C; tof-{120C. 'should be employed.

Iftheshainllength isfromtwo tot'six carbonatoms greatei than the 'y minimum, temperatures?" inithe range of 1'5" C.30- C. should be employed;z and-if Y the cha-inY length is greater than 'six carboiatoms beyond the minimum, temperatures from 25; 0950" C: are-fused. 1 It will be "appar-1* ent, then, that conditions of operation 'vary con-V siderably, conditions selected-"being vtli'ose appropriate forthe-formationof the desired plex'ad or@plexads.' v I Y plex is pumped, by means olf-pump 36, vthroughv In settler' 38j the slurry? of-'plexadY in' urea sol" vent is taken olf through line 49, heat exchanger 56 and heater 51 in solvent sweating Zone (or mixer) 46. A portion of the clear urea solventv may be removed from the center of 38 and recycled, through line-5l and pump 52, to mixer 32 if desired. l v

- It is to be understood that the gravity settler 38 may be replaced by other separation means such as a centrifuge orrotary lter, etc.

lThe mixture of solvent andl pflexad is heated in solvent sweating rone 46 to a temperature suflicient to decompose the major portion' of the plexadofthe n-octene-Z, While preserving the major portion 'of the plexad of n-octa-ne." They temperature employed in zone 46 'is related to that employed in mixer 32, and will'generally b'emaintained from 10 C. to 20 C. higher in zon'v46 than in`mixer V32.

The partially decomposed plexadsfurea sole" vent, and 5naphtha mixture is passed 'from 'zone 46,t1 ^lrough lineA 53V to settler 54. The naphtha containing plexand, noctane, and some' anti-'If plex,l n-octene7 2, is recycled throughv lines55 and' 33, ,tol mixer N`32. u A The slurry off'undecomposed plexadis withdrawn from the -bottom of settler 54throughfline'56, heat `Yexchatiger 51, heater 58' into settler 59. The plexad is thus heated hot v the naphtha may also be recycled tol fractionatorl' through line 6T. Plexand, n-octane, is recovered as bottoms through line 68.

Urea solution is recycled from the bottom of settler-59 through line 69, pump 16, heat exchangers 51 and 50, and line 5I.

Plexand ofany desired :purity may be obtained by either: (l) increasing the fraction of the totalplexad decomposed in the solvent sweating zone (46), or (2)- including a. multiplicity of alternating solvent sweating zones and settling zones (54) operatingin series.

VII. mLUs'mATivE EXAMPLES The following examples serve to illustrate, and not in any sense limit, the present invention.

(a) Separation of n-octene-.Zand n-octene-Z.m A mixture, 2()y parts by volume, comprising 50 volume per cent each of n-octene-l and n-octene-2, was agitated at 25 C. with 15() parts by volume of a saturated aqueous urea solution. The resulting mixture was allowed to stand for about 16 hours and then filtered. The recovered plexad was decomposed by Contact with water.

The. hydrocarbon recovered from the plexad comprised 13.5 parts by volume and was richer in n-octene-l than the original mixture, namely 69 volume per cent of n-octene-1.

(b) Separation of tft-octane from n-octene-l.- Six parts by volume of al 50- 50 volume per cent mixture of n-octane and noctene1, was agitated for 15 minutes at 25 C. with 30 parts by volume of a 67 per cent aqueous methanol saturated With urea and containing three parts by weight of excess solid urea. The resulting mixture was centrifuged, the upper layer poured off, andthe hydrocarbon recovered from the plexad by decomposition with Water. The recovered hydrocarbon, 1.5 parts by volume, contained 55 per cent of n-octane.

(c) Separation of 'rt-octane from n-octeue-Zr- The example shown above in (b) was repeated with a mixture containing 50-50 volume per cent of n-octane'and n-octene2. Here, the hydrocarbon recovered iromrthe plexad, 1.5 parts by volume,contained 61 per cent of n-octane.

(d) Separation of n-butyl stearato from nbutyl Clarita-A solution of 4 parts by'volume of n-butyl stearateand 4 parts (volume) of n-butyl oleate in 92 parts (volume) of iso-octane, was agitated at 50 C. for 30 minutes with 25 parts (volume) of an aqueous methanol solution saturated With urea at 65 C. The resulting plexad layer Was separated from the mixture, and decomposed by contacting the same with water. The ester recovered from the plexad contained 2 parts, (volume) of butyl stearate and 0.3 part (volume) of butyl oleate.

The same ester solution was stirred at 50 C. for 15() minutes with 100 parts by volume of the same urea solution. In this instance, the recovered ester contained 3.75 parts (volume) of butyl stearato and 1.4 parts (volume) of butyl 17 oleate. The antiplex contained 0.25 part of butyl stearate and 2.6 parts of butyl oleate.

The equilibrium concentrations of butyl stearate and of butyl oleate are shown by the following. Butyl stearate in iso-octane solvent on repeated treatment with a saturated solution of urea in methanol, can be removed to a concentration below 0.1 per cent by volume at 25 C. and to a concentration of 0.6 per cent at 50 C. In contrast, butyl oleate can be reduced in concentration to 0.8 per cent (volume) at 25 C. and 4.1 per cent at 50 C.

(e) Separation of di-n-heyi) succinate from dien-benzyl) maZeate.-The separation of saturated from unsaturated compounds is further illustrated by the experimental observation that the equilibrium concentration in the urea plexation of din-hexyl) succinate is below 0.1 per cent (volume) at 25 C., and only 3.5 per cent (volume) at 25 C. for dien-hexyl) maleate.

VIIL UTILITY From the foregoing description, it will be apparent that the invention has considerable application in the chemical and petroleum arts. For example, hydrocarbon mixtures containing straight chain parains, olens and polyolens can be separated into straight chain parafns, straight chain olens and straight chain polyoleiins, respectively.

Also, the invention is useful in effecting the separation of fatty acids (and their esters) of different degrees of unsaturation, such as those derived from various vegetable oils. This is particularly advantageous in providing concentrated drying oils or acids, relatively free of the nondrying oils and acids for the coating and resin industries. Thus, a mixture of stearic, oleic, linoleic and linolenic acids, or their esters with monohydric or dihydric alcohols, can be separated into their individual components, or into fractions relatively rich in the saturated components, and those rich in the more unsaturated components.

Another application is in making possible the separation of various long-chain saturated amines or amides from the related unsaturated amines or amides. This is illustrated by the separation of n-octadecylamine from mixtures containing the same and n-octadecenylamine. Still another application of the invention is in conjunction with the process described in related application Serial No. 115,512, filed concurrently herewith, wherein thiourea is shown as a plexor with highly-branched chain paralns and highly-branched chain olens as plexands. For example, with a mixture of straight chain parafins, highly-branched chain parailins and olens, it is possible to rst treat the mixture with thiourea to remove the highly-branched chain parafns in the form of their thiourea plexads and thereafter treat the remaining hydrocarbons with urea to effect separation of the straight chain parairins and olens. It will be understood that the same mixture can be plexated first with urea and then with thiourea.

This application is a continuation-impart of said copending application Serial No. 4,997, nled January 29, 1948.

Halogen compounds can be plexated from mixtures containing the same and form urea plexads, as described above and as described and claimed in application Serial No. 115,511. Compounds characterized by a nitrogen-containing substituent are also plexated from mixtures containing the same and form plexads with urea, as described above; this subject matter is also described and is claimed in application Serial No. 115,515. Sulfur-containing compounds are also plexated from their mixtures, and form plexads with urea, as described above and as described and claimed in application Serial No. 255,943, led November 13, 1951, as a continuation of application Serial No. 115,516 which has been abandoned. Plexation of compounds containing cyclic substituents, and urea plexads thereof, are described and are claimed in application Serial No. 116,593. Plexation with urea of various terminally substituted compounds from mixtures containing the same and non-terminally substitutedcompounds, described above, is also described and is claimed in application Serial No. 115,517.

Urea plexation of a non-terminally monosubstituted compound from mixtures containing the same and a non-terminally poly-substituted compound is described and is claimed in application Serial No. 115,513. Urea plexation of mixtures containing aliphatic compounds of different degrees of unsaturation is described and is claimed in application Serial No. 115,514. Plexation of mixtures containing aliphatic hydrocarbons of different degrees of unsaturation is described and is claimed in application Serial No. 266,547, led January 15, 1952, as a division of this application.

Said applications Serial Nos. 115,511; 115,513-

through 115,517 and 116,593 were led concurrently with this application on September 13, 1949.

I claim:

1. Crystalline complex of urea and a straight chain mono-olen having a minimum of six carbon atoms in the chain.

2. Crystalline complex of urea and a straight chain alpha mono-olefin having a minimum of six carbon atoms in the chain.

3. Crystalline complex of urea and a straight chain non-alpha mono-oleiin having a minimum of six carbon atoms in the chain.

4. Crystalline complex of urea and n-octene-l.

5. Crystalline complex of urea andn-octene-Z.

6. Crystalline complex of urea and n-decene-l.

'7. Crystalline complex of urea and n-dodecene-1.

8. Crystalline complex of urea and n-tetra- V decene-l;4

EVERETT GORIN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,569,984 Fetterly Oct. 2, 1941 2,300,134 Prieve et al Oct. 27, 1942 2,346,632 Wolfert et al Apr. 11, 1944 2,376,008 Piethof May 15, 1945 2,499,820 Fetterly Mar. 7, 1950 2,518,677 Garner et al Aug. 15, 1950 2,520,715 Fetterly Aug. 29, 1950 FOREIGN PATENTS Number Country Date 443,795 Great Britain Mar. 6, 1936 671,456 Great Britain May 7, 1952 pTHER REFERENCES Bengen, Reel 143 T. O. M. deposited in Library of Congress May 22, 1946, pages to v139. 

1. CRYSTALLINE COMPLEX OF UREA AND A STRAIGHT CHAIN MONO-OLEFIN HAVING A MINIMUM OF SIX CARBON ATOMS IN THE CHAIN. 